Physical-Mechanical Properties of γ-Irradiated SiC Ceramics for Radioactive Wastes Immobilization

The interest in silicon carbide (SiC-based) ceramics and composites as matrix material for nuclear waste immobilization is grown up. Long-term chemical durability and radiation resistance of SiC are important factors for radionuclides immobilization. Advantages of SiC-based ceramics as structural materials in nuclear applications are the high-temperature properties, high density and reduced neutron activation. The use of radiation resistant materials is a strong requirement for safe and environmentally beneficial energy system. The SiC ceramics stability under irradiation for temperatures up to 1273 K is also very important for nuclear power applications. The SiC matrices doped by additives of Cr, Si were fabricated using High Speed Hot Pressing Method. Additives content was in the range from 0.5 to 3 wt %. Microstructural characteristics of silicon carbide ceramics were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and infra-red spectroscopy (IR) methods. The results of microcracking under indentation conditions were revealed the lack of cracks in the SiC ceramics with Cr additives before and after irradiation process. In addition, it was demonstrated that samples of SiC with alloying additives Cr and Si possess high mechanical parameters under γ-irradiation process. The strength of ceramics increases with the uniform and fine-grained structure formation. The modification of phase composition and mechanical properties of the SiC ceramics with Cr and Si additives under γ-irradiation were analyzed for further development of radiation resistant and matrix materials for radioactive wastes immobilization

In vitro trial of the pilot prototype of the prostate mechanical imaging system

OBJECTIVES: To compare the sensitivity and accuracy of the mechanical imaging system (MI system) to that of the simulated digital rectal examination (DRE) in detecting nodules within fabricated rubber prostate phantoms. Mechanical imaging is a new technology for visualizing and characterizing tissues using mechanical strain and stress data. METHODS: Twelve rubber phantoms were designed to simulate human prostates. Ten phantoms contained hard nodules in various locations. Two phantoms contained no nodules. Each model was examined with the MI system by a urologist (R.E.W.) and research student. Three-dimensional images of the examined prostate phantoms with and without nodules were generated by the MI system software. Blind DRE was performed on each phantom independently by the urologist and student. The results of the MI examinations and DREs were compared for sensitivity in detecting the presence and location of nodules within the prostate phantoms. RESULTS: Three-dimensional MI images reconstructed from both the student and the urologist examination data demonstrated 100% of the nodules in the appropriate locations. The DREs by the urologist detected 83% of the nodules in the appropriate locations. The DREs by the student detected 67% of the nodules in the appropriate locations. CONCLUSIONS: The prostate MI system allowed the detection of nodules in the prostate phantoms with sensitivity exceeding that of an experienced urologist. In contrast to the DRE, the results of the MI examination appear to be independent of the operator's experience. Therefore, the MI system is a promising means of accurate, sensitive, objective, and recordable detection of hard nodules within the prostate

Primary cerebral lymphoma. Mental disorders after biopsy (case report)

The article reviews the literature on the diagnosis and treatment of primary lymphomas of the central nervous system and describes a case of mental disorder before and after surgery in a patient with lymphoma of the third ventricle. Using an interdisciplinary approach, psychopathological dynamics is analyzed taking into account the structural and functional state of the brain, which allowed to clarify the possible causes of mental disorders and methods of treatment. Acute onset of confusion and headache was associated with disorders of the liquor outflow, due to the localization of the tumor. The reason for the disintegration of consciousness after surgery was brain hypoxia and the instability of connections between cerebral structures associated with it. The peculiarity of the consciousness recovery could be determined by premorbid personal traits